Khao Sok National Park is the planet's oldest tropical rainforest, older than the Amazon jungle. Karst cliffs, emerald Cheow Lan Lake with floating bungalows, and unique flora create a lost world landscape.

Cheow Lan Lake is the park's gem: limestone cliffs rising from the water resemble Halong Bay in Vietnam. You can spend a night in a floating house, go kayaking, and trek through the jungle.

The park is famous for the rafflesia flower—the world's largest flower, blooming for just a few days a year. Best time to visit is the dry season (December-April). Accessible from Surat Thani or Phuket.